ADS8688: ADS8688 2nd Order low pass filter type / Group delay

Ulrich Oertel

Prodigy 20 points

Part Number: ADS8688

Hi Team,

which type of 2nd order LPF is used wihtin the ADS8688?

How is the Group delay of the fiter?

* constant or not constant?

Best regards, Ulrich

over 4 years ago

0 Dale Li over 4 years ago

TI__Mastermind 35550 points

Hi Ulrich,

It's analog LPF filter. The BW of this filter is 15kHz, so this is equivalent to a time constant of T=10us. Assuming 14-bit settling time => 9.7T, the delay will be around 97us which is constant (~12 for 16-bit settling).

Thanks&regards,

Dale

0 Ulrich Oertel over 4 years ago in reply to Dale Li

Prodigy 20 points

Hi Dale,

thank you for your prompt reply. Can you tell me the characteristic of the analog filter (Bessel, Butterworth, …) or the filter coefficients and design parameters (a,b,Q,A)?

Thank you very much, Ulrich

0 Dale Li over 4 years ago in reply to Ulrich Oertel

TI__Mastermind 35550 points

Hi Ulrich,

It's a passive RC filter as I know.

Thanks&regards,

Dale

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ADS8688: ADS8688 2nd Order low pass filter type / Group delay